Determining the date or code of a Zippo lighter is fun and easy. Because Zippo founder George G. Blaisdell offered a lifetime guarantee, the bottom of each Zippo lighter made since the mid-1950s was encoded/stamped with a variety of markings so he could identify which batch of lighters was being returned for repairs. What originally began as a quality control tool for Mr. Blaisdell, it has become a Zippo collector’s dream and a way to precisely date most Zippo lighters. You can date your Zippo by following the chart below: